The medical device industry produces a wide variety of electronic and mechanical devices for treating patient medical conditions, such as pacemakers, defibrillators, neurostimulators, and therapeutic substance delivery pumps. Medical devices may be configured to be surgically implanted or connected externally to a patient receiving treatment. Clinicians may use medical devices alone or in combination with therapeutic substance therapies and surgery to treat patient medical conditions. For some medical conditions, implantable medical devices provide the best and sometimes the only therapy to restore an individual to a more healthy condition and fuller life.
An implantable neurological stimulation system may be used to treat conditions such as pain, movement disorders, epilepsy, depression, pelvic floor disorders, gastroparesis, or a wide variety of other medical conditions. Such a neurostimulation system typically includes an implantable neurostimulator and a medical electrical stimulation lead. A lead extension may also be used. Medical electrical stimulation leads have one or more electrodes, which may be implanted within or proximate to a specific location in a patient to deliver stimulation to structures or tissues to a target location in the patient. Some therapies involve electrical stimulation of the brain, spinal cord, or pelvic floor. Still other therapies involve electrical stimulation of other sites in the patient.
As one example, deep brain stimulation (DBS) involves delivery of electrical stimulation to nerve structures in specific areas of the brain to either excite or inhibit cell activity. A stimulation lead is typically implanted at a desired location within the brain with relative precision using magnetic resonance (MR) imaging techniques and stereotactic guidance. DBS can be effective in the management of, for example chronic pain, movement disorders such as Parkinson's disease and essential tremor, epilepsy, and psychiatric disorders such as depression and obsessive-compulsive disorder.
Precise placement of the stimulation lead within the brain is important. In some applications, it is desirable to position the stimulation lead to deliver stimulation to a very small target site without stimulating adjacent brain tissue. If stimulation is not delivered with precision to a desired target site, adjoining areas may also be stimulated, which may lead to undesirable side effects.
Segmented rows of electrodes, in which each of the electrodes does not extend around the full periphery, e.g., circumference, of the lead body, may be desired for targeted stimulation or for efficient use of energy. With respect to targeted stimulation, electrodes in segmented rows may, for example, generate stimulation fields that are skewed in a particular radial direction from the lead, as opposed to the fields produced by ring electrodes, which are substantially equal in all radial directions when stimulating within homogeneous tissue. The ability to direct the stimulation field in this manner may permit particular stimulation targets to be activated, while avoiding other areas. This ability may be advantageous in the case of DBS, as well as other types of stimulation in which such precision is desired.